Climate change will hit crop yields in temperate and tropical regions earlier than first thought, a new study has found.

Researchers from the University of Leeds analysed the results of 1,700 published studies of the impact that climate change will have on the yields of rice, maize and wheat.

In 2007, a report from the Intergovernmental Panel on Climate Change (IPCC) concluded that harvests in temperate regions would be relatively unaffected by 2C of warming. It suggested some areas might even see a boost in productivity.

However, by looking at a data set twice the size of that used by the IPCC, the new study argues that this is not the case.

“As more data have become available, we’ve seen a shift in consensus, telling us that the impacts of climate change in temperate regions will happen sooner rather than later,” said Professor Andy Challinor, lead author of the study.

“Furthermore, the impact of climate change on crops will vary both from year-to-year and from place-to-place – with the variability becoming greater as the weather becomes increasingly erratic,” he added.

While the 2C of warming will mean “different countries winning and losing in different years […] the overall picture remains negative,” Challinor says.

The study suggests that on average the impact of climate change on crop yields will be increasingly damaging from the 2030s onwards.

The impact will become even greater in the second half of the century, when decreases of over 25% will become increasingly common, it warns.

The IPCC’s next report, due out later this month, is expected to investigate further the effects of global warming on food production.

According to a leaked draft – which may vary from the final release – average crop yields will drop by 2% by the end of the century, while global demand for food rises by 14% every year by 2050.

The report warns this might fuel conflict, cause poverty and lead to mass migration, as well as causing a 2% global economic loss.